Most of the tunnel equipment and systems requires electrical energy to operate. Therefore, equipment for supplying power to the tunnel must be installed. This installation has to satisfy two essential requirements:
The power required for supplying a tunnel is directly related to the nature and number of equipment installed in it. Depending on the amount of electrical energy required (kWh), power may be supplied in low voltage or high voltage.
Each country has its own regulatory requirements with regard to tunnels and a specific structure in terms of distribution networks: therefore, the architectures retained may be significantly different in tunnels with similar characteristics. However, some identical principles can be noted, such as: